N 19)
angle (21x+6) is equal angle 90°-----> by alternate exterior angles
so
21x+6=90--------> 21x=84----------> x=4°
the answer N 19) is 4 degrees
N 20)
angle 75 is equal angle 11x-2-----> by corresponding angles
so
11x-2=75-----> 11x=77--------> x=7°
the answer N 20) is x=7 degrees
N 21)
angle 60 is equal angle (8x-4)------> by alternate interior angles
so
8x-4=60-----> 8x=64--------> x=64/8-----> x=8°
the answer N 21) is x=8 degrees
N 22)
angle (x+139) is equal to angle 132-----> by alternate interior angles
so
x+139=132-------> x=132-139--------> x=-7 °
the answer N 22) is x=-7 degrees
N 23)
angle (-1+14x) is equal to angle (12x+17)----> by alternate exterior angles
so
-1+14x=12x+17------> 14x-12x=17+1----> 2x=18----> x=9
the answer N 23) is x=9 degrees
N 24)
angle (23x-5) is equal to angle (21x+5)----> by corresponding angles
so
23x-5=21x+5-----> 23x-21x=5+5-----> 2x=10-----> x=5
the answer N 24) is x=5 degrees
N 25)
angle (x+96) and angle (x+96)-------> are supplementary angles
so
x+96+x+96=180--------->2x+192=180------> x=-6°
the angle indicated in bold is (-6+96)=90°
N 26)
angle (20x+5) and angle (24x-1)-------> are supplementary angles
so
20x+5+24x-1=180------> 44x=176-----> x=4°
the angle indicated in bold is (20*4+5)=85°
N 27)
angle (6x) is equal to angle (5x+10)--------> by corresponding angles
so
6x=5x+10------> 6x-5x=10------> x=10
the angle indicated in bold is (6*10)=60°
N 28)
angle (x+109) and angle (x+89) are supplementary angles
so
x+109+x+89=180----> 2x=-18-------> x=-9
the angle indicated in bold is (x+89)----> -9+89=80°
-5/12 would be the answer
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Answer:

Step-by-step explanation:
The sum of an infinite geometric series is expressed according to the formula;
where;
a is the first term of the series
r is the common ratio
If the sum of an infinite geometric series is three times the first term, this is expressed as 
Substitute
into the formula above to get the common ratio r;


open the parenthesis

subtract 3 from both sides

<em>Hence the common ratio of this series is </em>
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